One step of the in vitro fertilization (I.V.F.) program is the removal of an ovum (egg) from the follicle (egg sac) of a woman patient. This is usually achieved by piercing the follicle with one end of a long hollow tapered conduit or needle and applying a vacuum to the other end of the needle so as to withdraw the ovum from the follicle together with the fluid contained in the follicle and transfer the ovum and fluid to a receptacle, such as a test tube. For a variety of reasons, the ovum is sometimes not completely transferred. When this occurs, it is necessary to introduce fluid into the follicle in an attempt to flush out the ovum and thus attempt the withdrawal again.
In order to reduce the risk of injury to the patient, the follicle and the ovum, it is preferable to have a method that allows both the delivery of fluid and aspiration of fluid through a single needle or conduit. One way of achieving this is to have a control device attached to the needle or conduit, said device having two inlets, one to deliver the flushing fluid and one to aspirate fluid from the follicle.
A number of such control devices are currently available, but they do have certain disadvantages. For example, they may incorporate plastic valves with compressible fittings that may leak after heat sterilization. Alternatively, they may be constructed entirely from metal which means that they are difficult and expensive to manufacture. Additionally, such control devices may be bulky and difficult for the surgeon to handle during the I.V.F. procedure.